More than 100,000 individuals worldwide are implanted with an infusion system configured to deliver therapeutic agent to the cerebrospinal fluid (CSF) of a patient. Such systems typically have a reservoir containing a supply of therapeutic substance awaiting delivery to the patient's CSF. A pump may be fluidly coupled to the reservoir for creating fluidic pressure to facilitate delivery of the therapeutic substance. A catheter provides a pathway for delivering the therapeutic substance to the CSF of the patient. All parts of the infusion system need to operate adequately to ensure proper delivery of therapeutic substances using the system.
While perhaps the least complex component of an infusion system, catheters can have operational problems or can develop operational problems. For example, catheters may be placed in the wrong location when originally deployed or the catheters may move (migrate) over time such that fluids (e.g., therapeutic substances) delivered through the catheters are not delivered to the originally intended delivery site (e.g., a CSF compartment).
Catheters can also become obstructed or clogged during use. A partial or complete blockage could prevent an adequate supply of the therapeutic substance from reaching the intended delivery site of the patient.
Catheters can also leak due to cuts, tears, etc. A leak, small or large, can also prevent some or all of the therapeutic substance from reaching the selected internal delivery site of the patient and may result in therapeutic substance being delivered to unintended sites, which may create further issues.
Some infusion systems have been proposed which include pressure sensors capable of monitoring pressure in the catheter to determine whether a catheter malfunction has occurred. However, to date, methods and systems for determining catheter status of the more than 100,000 already implanted infusion devices that deliver agents to a patient's CSF, where the methods and systems employ pressure sensors external to the device or patient, have been lacking.